We all "know" that smoking causes chronic obstructive pulmonary disease (COPD), but the fact is some non-smokers develop the condition, and some smokers do not. What makes the difference?
One of the ongoing mysteries of medical science is the real relationship between smoking and chronic obstructive pulmonary disease, also known as COPD. There are smokers who do not develop COPD. There are non-smokers who do. Understanding what protects smokers or harms non-smokers, with regard to the eventual development of chronic obstructive pulmonary disease, can enable good lifestyle choices.
What Is COPD?
Chronic obstructive pulmonary disease is defined by a triad of symptoms. People who have COPD typically suffer:
- Chronic bronchitis, which is defined as a productive cough (coughing up phlegm) that lasts two years or more.
- Emphysema, a permanent enlargement of the alveoli (air sacs) of the lungs, which makes it more difficult for them to capture air.
- Asthma, a tightening of the passages leading to the alveoli, so less air can get into the lungs.
People who have COPD usually wake up coughing every morning. The cough up clear, colorless sputum. They are prone to bouts with severe respiratory illnesses. Colds and flu produce severe symptoms. They usually don't have trouble catching their breath until the sixth decade of life, after the age of 50, although this is the best known symptom of the disease.
COPD usually involves both chronic bronchitis and emphysema, but these two components of the overall problem may not be expressed to the same degree.
People who have more of a problem with chronic bronchitis tend to be obese. People who have more of a problem with emphysema tend to be thin but barrel-chested. People who have more of a problem with chronic bronchitis tend to cough up more phlegm and to suffer swelling. People who have more of a problem with emphysema may cough very little, but they tend to have to breathe through pursed lips and they need to sit up to breathe comfortably.
Differences Between Smokers And Non-Smokers With COPD
Chinese researchers have found that there are significant differences between smokers who develop COPD and non-smokers who develop COPD. Smokers tend to have more emphysema symptoms. Non-smokers tend to have more bronchitis symptoms. Smokers will have difficulty breathing even if they manage to overcome asthma and bronchitis. Non-smokers will be greatly improved just by eliminating the factors that aggravate asthma (cold drafts, dust, irritant chemicals in the air, and allergnes).
Smokers need to reduce asthma and bronchitis symptoms, but they also need emphysema treatments.
Smokers and non-smokers also respond differently to COPD treatment. By the end stages of COPD, there's not a lot that can be done. Whether or not you have ever smoked, you are likely to need supplemental oxygen. Even with supplemental oxygen, your tissues are likely to be poorly oxygenated. Your lungs just can't get the oxygen into your bloodstream. A condition known as respiratory acidosis may develop, and respiratory failure comes soon thereafter.
Non-smokers who quit smoking early enough in the course of COPD don't get better, but they don't get worse. The loss of the ability of the air sacs to contract and hold air so the bloodstream can absorb oxygen is diminished, but the situation is less likely to become critical. This doesn't answer the question of why a non-smoker should ever develop COPD at all.
Why Do Some Non-Smokers Develop COPD?
Smoking is the main cause of COPD, and smoking cessation is the best way to stop the progression of the disease for most people. That leaves the open question, why do non-smokers ever develop COPD at all?
Research in China has traced a number of factors to the development of COPD in people who have never smoked. In the People's Republic of China, over 8 percent of the population has the disease, but 27 percent of people with COPD never smoked, and of this group, about 70 percent are women. The factors that predispose non-smokers to chronic pulmonary problems include:
- Exposure to smoke, particularly from cooking fires. Women who prepare meals over wood or kerosene stoves and men who are cooks in restaurants are at special risk for COPD, because of the particulate matter in the smoke.
- People who lived in houses heated by coal fires without chimneys are at special risk of developing COPD. Installing chimneys reduces the risk of COPD.
- People who lived in the dustier cities of western China were more susceptible to COPD than people who lived in Shanghai.
People in other parts of the world, of course, aren't as likely to heat their homes with coal fires in the middle of the floor or to cook over wood and kerosene. Surely they don't develop COPD as often as people in China, one might think.
However, COPD is actually more common in Europe than in China. One study found higher rates of emphysema in the Netherlands than in China. The reason for those higher rates could not be electric stoves and steam heat during winter, so what would the common factors in Europe be?
- People in Europe who develop COPD are more likely to have had serious respiratory infections as children.
- People in Europe who develop COPD are more likely to have started smoking before the age of 18.
- People in Europe who develop COPD are more likely to have had pneumonia as adults.
This means that it isn't just exposure to tobacco smoke and other kinds of fumes that cause COPD, it can also be lower respiratory tract infections. A bout with pneumonia can lead to higher risk of COPD. Also, data that locate the highest rate of COPD in the world in Cape Town, South Africa, 22 percent, suggest that genetic factors can also doom some people to deal with the disease.
If you have ever been the caretaker for someone who has advanced COPD, you will surely not want to go through that disease yourself. The most important thing to do to prevent the disease still is to stop smoking if you currently smoke. Smoking a pack a day for more than 10 years becomes a significant risk factor for COPD. However, even if you don't smoke:
- Get a flu shot every year. Every time you get influenza, you increase your risk for COPD.
- If you are over 50, get the vaccination for bacterial pneumonia every five years. In the US, you need a vaccination with a medication called Prevnar-13.
- Even if you do get a flu shot, be meticulous about washing your hands during flu and colds season so you do not get a virus.
- Don't spend all your time in front of a barbecue pit or a fireplace. Even well-ventilated fires release large amounts of particulate matter.
- If you work in dusty conditions or around chemical fumes, take every available precaution to minimize your exposure.
Sources & Links
- Zhang J, Lin XF, Bai CX. Comparison of clinical features between non-smokers with COPD and smokers with COPD: a retrospective observational study. Int J Chron Obstruct Pulmon Dis. 2014. 9:57-63. doi: 10.2147/COPD.S52416. Epub 2014 Jan 8.
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